Fix requests version range

It was more permissive than docker-py's, resulting in an incompatible
version (2.5.x) being installed.

Signed-off-by: Aanand Prasad <[email protected]>

setup.py

@@ -27,7 +27,7 @@ def find_version(*file_paths):
 install_requires = [
     'docopt >= 0.6.1, < 0.7',
     'PyYAML >= 3.10, < 4',
-    'requests >= 2.2.1, < 3',
+    'requests >= 2.2.1, < 2.5.0',
     'texttable >= 0.8.1, < 0.9',
     'websocket-client >= 0.11.0, < 1.0',
     'docker-py >= 0.6.0, < 0.8',